Process for the direct synthesis of organotin compounds and their use

ABSTRACT

The invention relates to a process for the direct synthesis of organotin compounds of the formula 
     
         R.sub.n SnCl.sub.4-n 
    
     wherein 
     n=1-4, and, 
     R=a linear or branched or cycloaliphatic alkyl having 4-18 C atoms, 
     by reacting metallic tin with alkyl chlorides, characterized in that the reaction is carried out in the presence of amines of the general formula 
     A) R 1   a  N [(CH 2  CH 2  O) m  CH 2  CH 2  OR 2  ] 3-a   
      and/or ammonium chlorides of the formula 
     B) R 1   b  N [(CH 2  CH 2  O) m  CH 2  CH 2  OR 2  ] 4-b   Cl   
     wherein 
     a=0, 1 or 2; 
     b=0, 1, 2 or 3; 
     R 1  =linear or branched or cycloaliphatic alkyl having 2 to 24 C atoms, aryl, alkyl aryl or substituted aryl and, if a=2, or b=2 or 3, the R 1  groups may be the same or different; 
     R 2  =H, linear or branched alkyl having 1 to 20 C. atoms, aryl, substituted aryl or alkyl aryl; and 
     m=1-20.

DESCRIPTION

The present invention relates to a process for the direct synthesis oforganotin compounds of the general formula

    R.sub.n SnCl.sub.4-n                                       ( 1)

wherein

n=1-4, and,

R=linear or branched or cycloaliphatic alkyl having 4 to 18 C atomsincluding mixtures of such compounds and their use.

The synthesis of organotin compounds, in particular organotin chloridesof the above-mentioned formula (1) is customarily predominantly carriedout industrially according to the following methods:

reaction of tin tetrachloride with aluminum alkylene

Grignard synthesis

In the direct synthesis from tin metal according to the reactionequation (2) indicated in the following the balance is on the left side,and any significant yields of desired compounds cannot be obtainedwithout suited catalysts.

    Sn+2R'Cl⃡R'.sub.2 SnCl.sub.2, (R'=alkyl)       (2)

The alkyl tin chlorides lead to the following secondary reactions withalkyl chlorides and/or tin metal:

(a) R'₂ SnCl₂ +Sn+R'Cl→R'₃ SnCl+SnCl₂

(b) R'₂ SnCl_(2+Sn+) 2 R'Cl→R'₄ Sn+2SnCl₂

(c) 4R'₃ SnCl+Sn→3R'₄ Sn+2SnCl₂

Moreover, autocomproportioning reactions are also possible:

    R'.sub.3 SnCl+R'SnCl.sub.3 →2R'.sub.2 SnCl.sub.2    ( 3)

and also the formation of by-products, in particular from SnCl₂ :

    SnCl.sub.2 +R'Cl→R'SnCl.sub.3                       ( 4)

Thus the following compounds:

    R'.sub.4 Sn, R.sub.3 'SnCl, R'SnCl.sub.2, R'SnCl.sub.3 and SnCl.sub.2

may be present in the reaction mixture in the synthesis described above.

In this case, all these compounds are of an industrially usableimportance since they can be converted to desired final products bymeans of known reactions:

    R'.sub.4 Sn+SnCl.sub.4 →2R'.sub.2 SnCl.sub.2

    R'.sub.3 SnCl+SnCl.sub.4 →R'SnCl.sub.3 +R'.sub.2 SnCl.sub.2

    SnCl.sub.2 +R'Cl→R'SnCl.sub.3

If one or several of the aforementioned secondary reactions take placetogether with the main reaction or overlay the same, variable amounts oftin halide (SnCl₂) are formed, which in turn can be recovered alone orused for further reactions.

Processes of the direct synthesis of organotin halides have already beendescribed in numerous patents, in particular using alkyl bromides andiodides as starting halides.

It is known, e.g. from U.S. Pat. No. 3,857,868, that the reaction of thedirect synthesis is promoted by the presence of tertiary amines and/orquaternary ammonium salts, it being possible that the latter ones areformed "in situ" from the used tertiary amine and the used alkyl halide.

The reaction is furthermore promoted by the presence of polar solventsand/or catalysts which are capable of reacting with the tin. For thispurpose, alcohols, esters or amines are occasionally used. In the directsynthesis of alkyl tin halides, alkyl chlorides have a low reactivitywith respect to metallic tin as compared with the corresponding alkylbromines and iodides. The reaction rate and the yield of desiredreaction product increases furthermore with increasing number of the Catoms in the alkyl chain within the alkyl chlorides, it being alreadydifficult to carry out the direct synthesis in the case of the use of C₄alkyl chloride (butyl chloride). The alkyl tin chlorides are thereforeproduced industrially from tin tetrachloride by means of reaction withtrialkyl aluminum compounds, Grignard synthesis or modified Wurtzsynthesis, which requires a considerable additional expenditure of costsand process steps.

The present invention is based on the object of making available aprocess for the direct synthesis of organotin compounds using alkylchlorides with four or more C atoms, which can be carried out simply andwith good yield.

This object is accomplished according to the invention by a process forthe type mentioned at the beginning, which is characterized in that thereaction is carried out in the presence of amines of the general formula

A) R¹ _(a) N [(CH₂ CH₂ O)_(m) CH₂ CH₂ OR² ]_(3-a)

and/or ammonium chlorides of the formula

B) R¹ _(b) N [(CH₂ CH₂ O)_(m) CH₂ CH₂ OR² ]_(4-b) ^(Cl)

wherein

a=0, 1 or 2;

b=0, 1, 2 or 3;

R¹ =linear or branched or cycloaliphatic alkyl having 2 to 24 C atoms,aryl, alkyl aryl or substituted aryl and, if a=2, or b=2 or 3, the R¹groups may be the same or different;

R² =H, linear or branched alkyl having 1 to 20 C atoms, aryl,substituted aryl or alkyl aryl; and

m=1-20.

The present invention relates in particular to the direct synthesis oforganotin compounds starting from alkyl chlorides, the use of which hasbeen more difficult so far due to their lower reactivity than that ofthe corresponding bromides and iodides and offers moreover the advantageof the use of less expensive starting substances, namely alkylchlorides, without it having to be worked under pressure as this isnecessary, as a rule, with alkyl halides with less than 4 C atoms in thealkyl part due to their low boiling points.

It became surprisingly apparent according to the invention that thedirect synthesis of organotin compounds can be carried out veryeffectively and efficiently by means of the reaction of metallic tinwith alkyl chlorides, if the reaction is carried out in the presence ofamines of the aforementioned formula A or ammonium chlorides of theaforementioned formula B. In the case of the use of the amines of theformula A quaternary ammonium salts are formed in situ here.

The reaction is suitably carried out at a temperature between 20° and200° C., preferably between 140° and 190° C. in the presence of 0.1 to 4mole of the amine of the formula A and/or of the ammonium chloride ofthe formula B per gramme atom of tin. The reaction time is suitably 3 to24 hours, preferably 6 to 10 hours. The reaction is furthermore suitablycarried out with 1 to 6 mole, preferably 2 to 3 mole, of alkyl chlorideper gramme atom of tin.

Although it is not necessary, the presence of traces of I₂ or Br₂, inparticular in amounts between 10⁻³ and 0.2, preferably 10⁻² mole of I₂or Br₂ per gramme atom of tin is often advantageous for the reaction.The I₂ and/or BR₂ can be directly supplied to the reaction or can beadded in dissolved fashion and together with the alkyl chloride.

After complete reaction, the amine and/or ammonium chloride can berecovered subsequently by known chemical processes and be used again.

It is important for a good success of the reaction, although it is notimperative, that the alkyl chloride is not present in such a highconcentration that it becomes active as a solvent. Therefore the alkylchloride is preferably slowly added to the reaction drop-wise at theselected reaction temperature so that the selected reaction temperatureis maintained. The reaction may be carried out in the presence of suitedsolvents to keep the reaction mixture sufficiently fluid.

After the reaction, the reaction mixture is customarily filtered toseparate non-reacted tin. It can then be washed with acetone and driedand be used again.

The filtrate can be distilled at reduced pressure for recovery of thenon-reacted alkyl chloride and/or the possibly used solvent.

In the case of the use of the amine and/or of the ammonium chloride inan amount being equimolar to the tin, mixtures of dialkyl tindichloride, trialkyl tin chloride and tetraalkyl tin and tin dichlorideare formed. In the case of the use of the amine and/or of the ammoniumchloride in excess to the equimolar amount trialkyl tin chloride ischiefly obtained and to a variable extent tetralalkyl tin and tindichloride are additionally obtained. In the case of the use of theamine and/or of the ammonium chloride in catalytic amounts of less than0.5 mole, in particular 0.1 to 0.33 mole per gramme atom of tin, almostpure dialkyl tin dichloride is obtained and in small variable amountsalkyl tin trichloride is obtained as reaction product.

The organotin compounds produced according to the invention are inparticular suited as intermediate products for the production ofthermostabilizers, e.g. alkyl tin mercapto compounds, for PVC resins.

The following examples explain the invention.

The ratio of the conversion of the used metallic tin is indicated in %,all types of the tin compound, in which the tin is present innon-metallic fashion, e.g. also possibly present tin dichloride in thereaction product being rated as "usable" product.

The reaction products were analyzed using thin-layer chromatography.

EXAMPLE 1

Tin powder (36 g; 0.3 mole) is suspended at room temperature togetherwith octyl chloride (14.9 g; 0.1 mole) and I₂ (0.4 g; 1.57×10⁻³ mole) inamine of the average composition C₁₃ H₂₇ N[(CH₂ CH₂ O)₁,3 CH₂ CH₂ OH]₂(120.3 g; 0.3 mole).

The reaction mixture is heated to 170° to 175° C. under thoroughstirring and further octyl chloride (120.1 g; 0.81 mole) is added atthis temperature in the course of 6 hours, the said temperature beingmaintained during the entire feed time. After the addition of the totalamount of octyl chloride, the reaction is continued under stirring at170° to 175° C. for further 3 hours.

After the expiration of this time cooling to 80° to 90° C. is carriedout and the non-reacted tin is filtered out, which is then washed withacetone on the filter, dried and weighed. The converted share of theused tin proves to be 84%.

The analysis of the product by means of thin-layer chromatography (TLC)shows as main components R₃ SnCl and R₂ SnCl₂, the first beingpredominant, and traces of RSnCl₃ and R₄ Sn.

EXAMPLE 2

Tin powder (60 g; 0.5 mole) is suspended together with octyl chloride(14.9 g; 0.1 mole) and I₂ (0.635 g; 2.5×10⁻³ mole) in amine of theaverage composition C₁₃ H₂₇ N[(CH₂ CH₂ O)₁,3 CH₂ CH₂ OH]₂ (40.1 g; 0.1mole). The reaction mixture is heated to 175° C. and further octylchloride (148.5 g; 1.0 mole) is added at this temperature under thoroughstirring in the course of 6 hours.

After the addition, the reaction is continued for 3 hours under stirringat 175° C. Then cooling to 80° to 90° C. is carried out and thenon-reacted tin is filtered out, which is washed with acetone on thefilter, dried and weighed.

The converted share of the used tin is 65%.

The TLC analysis shows that the product consists mainly of R₂ SnCl₂ andRSnCl₃, predominantly of the first component. A certain amount of R₃SnCl is also present, traces of R₄ Sn cannot be detected.

EXAMPLE 3

Tin powder (36 g; 0.3 mole) is suspended together with octyl chloride(178.2 g; 1.2 mole) and I₂ (0.76 g; 3×10⁻³ mole) intris-(3,6-dioxaheptyl) amine (194 g; 0.6 mole) and kept at 175° C. underthorough stirring for 12 hours.

At the end of the reaction cooling to 80° to 90° C. is carried out andthe non-reacted tin is filtered out, which is washed, dried and weight.

The converted share of the used tin is 78%. The TLC analysis shows thatthe product consists mainly of R₃ SnCl and R₂ SnCl with a greatpredominance of the first component.

EXAMPLE 4

Tin powder (36 g; 0.3 mole) is suspended together with octyl chloride(14.9 g; 0.1 mole) and I₂ (0.76 g; 3×10⁻³ mole) in diethyl ethoxyethanol amine (96.75 g; 0.4 mole).

The reaction mixture is heated to 170° to 175° C. under thoroughstirring. Further octyl chloride (74.2 g; 0.5 mole) is added at thistemperature in the course of 4 hours. After the addition, the reactionis continued under stirring at 175° C. for further 4 hours.

After cooling to 80° to 90° C. the non-reacted tin is filtered out,washed, dried and weighed. The converted share of the used tin is 66.6%.

The TLC analysis shows that the product consists of R₃ SnCl, R₄ Sn andR₂ SnCl₂ with predominance of the first component.

EXAMPLE 5

Tin powder (24 g; 0.2 mole) is suspended together with octyl chloride(118.8 g; 0.8 mole) and I₂ (0.51 g; 2× 10⁻³ mole) in amine of theaverage composition C₁₈ H₃₇ N[CH₂ CH₂ O)₃,5 CH₂ CH₂ OH]₂ (66.3 g; 0.1mole).

The reaction mixture is kept at 160° C. under thorough stirring for 12hours. After cooling, the non-reacted tin is filtered out, washed, driedand weighed.

The converted share of the used tin is 81.8% and the product consistsmainly of R₃ SnCl, together with R₂ SnCl₂.

EXAMPLE 6

Tin powder (36 g; 0.3 mole) is suspended together with I₂ (0.76 g;3×10⁻³ mole) in amine of the average composition C₁₃ H₂₇ N[(CH₂ CH₂O)₁,3 CH₂ CH₂ OH]₂. During the course of 8 hours butyl chloride (83.3 g;0.9 mole) is added dropwise to the reaction mixture heated to 170° to175° C. by means of a probe reaching under the surface of the reactionmixture in such fashion that the reaction temperature is maintained.

After the expiration of this time the reaction mixture is filtered at80° C. The non-reacted tin is washed on the filter, dried and weighed.

The converted share of the used tin is 76.4%.

The product consists mainly of R₃ SnCl.

EXAMPLE 7

Tin powder (36 g; 0.3 mole) is suspended in diethyl ethoxy ethanol amine(24.3 g; 0.15 mole) together with I₂ (0.76 g; 3×10⁻³ mole). Butylchloride (83.3 g; 0.9 mole) is added dropwise under stirring in thecourse of 7.5 hours in the same fashion as explained in example 6. Afterthe addition, the reaction mixture is cooled and the non-reacted tin isfiltered out, washed, dried and weighed.

The converted share of the used tin is 64.5%.

The product consists mainly of R₃ SnCl together with R₄ Sn and R₂ SnCl₂.

EXAMPLE 8

Tin powder (60 g; 0.5 mole) is suspended in molten ammonium saltdiethyl-bis-(ethoxy ethanol) ammonium chloride (71.5 g; 0.25 mole).Heating to 180° C. is carried out and octyl chloride (185.5 g; 1.25mole) is added dropwise during 5 hours.

After the addition of the total amount of octyl chloride, the reactionis continued at 180° to 185° C. under stirring for further 7 hours.

After the expiration of this time, cooling to 80° to 90° C. is carriedout and then the non-reacted tin is filtered out, which is then washedon the filter, dried and weighed.

The converted share of the used tin proves to be 86.5%.

The product consists of R₃ SnCl and R₂ SnCl₂, with slight predominanceof the first component.

EXAMPLE 9

Amine of the formula (C₄ H₉)₂ N(CH₂ CH₂ OCH₂ CH₂ OCH₂ CH₂ OH) (28.8 g;0.11 mole) is heated to 130° C. together with I₂ (0.63 g; 2.5×10⁻³mole).

Tin powder (40 g, 0.34 mole) is suspended at this temperature anddodecyl chloride (143.4 g; 0.7 mole) is added dropwise in the course of7.5 hours and the temperature is raised up to 180° to 190° C.

The reaction is still continued for further 2.5 hours.

After cooling to 80° to 90° C., the non-reacted tin is filtered out,washed, dried and weighed. The converted share of the used tin is 90%.The product consists mainly of R₂ SnCl₂ and a small amount of R₃ SnCl.

We claim:
 1. A process for the direct synthesis of organotin compoundsof the formula

    R.sub.n SnCl.sub.4-n

wherein n=1-4, and R=a linear or branched or cycloaliphatic alkyl having4-18 C atoms, by reacting metallic tin with alkyl chlorides,characterized in that the reaction is carried out in the presence ofamines of the general formula A) R¹ _(a) N [(CH₂ CH₂ O)_(m) CH₂ CH₂ OR²]_(3-a) and/or ammonium chlorides of the formula B) R¹ _(b) N [(CH₂ CH₂O)_(m) CH₂ CH₂ OR² ]_(4-b) ^(Cl) whereina=0, 1 or 2; b=0, 1, 2 or 3; R¹=linear or branched or cycloaliphatic alkyl having 2 to 24 C atoms,aryl, alkyl aryl or substituted aryl and, if a=2, or b=2 or 3, the R¹groups may be the same or different; R² =H, linear or branched alkylhaving 1 to 20 C atoms, aryl, substituted aryl or alkyl aryl; andm=1-20.
 2. A process according to claim 1, characterized in that R² is alinear or branched alkyl having 1 to 4 carbon atoms.
 3. A processaccording to claim 1, characterized in that m is 1-10.
 4. A processaccording to claim 1, characterized in that butyl chloride, octylchloride or dodecyl chloride is used as alkyl chloride.
 5. A processaccording to claim 1, characterized in that the amine and/or theammonium chloride is used in a ratio of 0.1 to 0.33 mole per gramme atomof tin.
 6. A process according to claim 1, characterized in thatequimolar amounts of amine and/or ammonium chloride are used withrespect to the tin.
 7. A process according to claim 1, characterized inthat the amine and/or ammonium chloride are used in excess to theequimolar amount with respect to the tin.
 8. A process according toclaim 3 characterized in that m is 1-3.